Thermostatic idle



y 1961 L. B. READ 2,986,380

THERMOSTATIC IDLE Filed Dec. 30, 1957 ll] /05 76 9 93 m5 94 86 a4 77 J I07 9/ 94 87 as a] //4 79 8 az 76 72 8/ W $4 FIG.2.

INVENTOR. LELAND B. READ gmz/ww ATTORNEY United States Patent THERMOSTATIC IDLE Leland B. Read, Normandy, 'Mo., assignor to ACF Industries, Incorporated, New York, N.Y., a corporation of New Jersey Filed Dec. 30, 1957, Ser. No. 705,983

14 Claims. (Cl. 261-39) This invention relates to fuel systems for internal combustion engines, and more particularly to an improved system for maintaining a satisfactory fuel-air combustible mixture during idle operation.

In fuel systems for internal combustion engines equipped with carburetors, fuel and air is metered by the carburetor to form a combustible mixture. The mixture is drawn through an induction system into the engine. The induction system includes a carburetor mixture conduit in which the fuel and air is mixed. The mixture conduit normallyincludes an air horn equipped with an air cleaner for the admission of clean air to the induction system, a choke valve in the air horn, and a throttle valve downstream from the choke valve. Carburetors are normally provided with two basic fuel systems: first, an idle system which functions when the throttle valve is closed or nearly closed to provide a substantially constant, small speeds above idle speed. -By opening the throttle valve from the closed position, a transition from the idle fuel system operation to the main fuel system operation is effected. -In order that this transition be as smooth as possible, an accelerating fuel pump system isusuallyprovided for furnishing a small additional quantity of fuel during the transition period. All of the fuel systems are usually supplied from a fuel chamber inthe carburetor, the level of the fuel in thecarburetor being controlled by a float and needle valve assembly. The fuel chamber is normally vented, either to the atmosphere, or by internal vents, such as a balance tube, into the air horn to maintain substantially the same pressure in the air hornandin the fuel chamber.

During idle operation the desired fuel-air mixture is substantially richer to keep the engine operating, as is well understood in the art. Should the fuel-air mixture become too rich during idle operation, the engine will run roughly, and may stall. The mixture ratio provided by the idle fuel system during idle operation is substantially constant and determined by manual adjustments, but certain factors may cause variations. For example, excessive richness can result from fuel vapors passing from the fuel chamber through internal vents and into the air horn, particularly during hot, prolonged idle operation. Also, if the air entering the mixture conduit is overly hot, the air density will be reduced sufliciently that the limited quantity of air mixing With the fuel will provide an idle mixture far too rich for proper engine operation.

Briefly, the present invention relates to a hot idle compensator system for a carburetor provided with a by-pass passage from the air horn to a mixture portion downstream of a substantially closed throttle valve to admit increasing metered volumes of clean air to the mixture portion responsive to increases in air temperature in the air horn during idle operation of an internal combustion engine. The passage is controlled by a temperature responsive metering valve in the air,horn. It isdesirable that the valve be as nearly as possible responsive only to the temperature of the incoming air but engine suction also affects its operation. Therefore, when'the incoming air temperature is exceedingly high, the valve opens, permitting anadditional quantity of air to mix with the fuel from the idle system and provide a smoother, more consistent idle operation of the engine. During idle operation in the normal temperature range, the valve opens responsive to a drop in engine suction to admit additional air to the mixture portion and thereby slightly increasing engine speed.

It is therefore an object of this invention to provide a smoother, more consistent idle operation in an internal combustion engine.

Another object of this invention is to provide an improved fuel system for an internal combustion engine.

Another object of this invention is to assure the admission of sufficient air during idle operation to provide a proper fuel-aircombustible mixture for an internal combustion engine throughout a varying range of air temperaturesabove normal operating temperature.

Another object of this invention is to provide an improved temperature responsive valve ,for controlling the flow of air or other fluid.

Another object of this invention is to provide an improved temperature responsive metering valve which is simple and inexpensive to manufacture, and is dependable in operation.

Another object of this invention is to provide a simpler and improved anti-stall device for the fuel system of an internal combustion engine.

Additional objects and advantages will be apparent from the following description and drawings, in which:

Fig. 1 is a schematic partial sectional view inelevation of a carburetor illustrating an embodiment of the invention including a temperature responsive valve assembly shown inthe closed position;

Fig. 2 is an enlarged sectional view of a portion of Fig. 1, illustrating the valve assembly in an openposition;

Fig. 3 is a sectional elevation view of another embodiment of a portion ofavalve assembly;

Fig. 4 is a sectional elevation view of still another embodiment of a valve assembly; and

Fig. Sis a plan view of the valveassembly illustrated in Fig. 4.

.Referring to the drawings, Fig. lillustrates the operative environment of the invention and onemodification vof an airvalve assembly. A dual barrel carburetor 1 includes a base section 2 having a flange 3 for attaching thecarburetor to an intake manifold on an engine ,(-not shown), a body section 4 including afuel chamber 6 and a venturicluster 7, anda cover section 8 including an .air horn 9 having a reinforced rim 11 to which an air cleaner (not shown) .is secured. Incorporated in the base, body, and cover sections is a pair of mixture or induction conduits 12, only one ofthe conduits being illustrated. The base section of mixture conduit 12-has mounted therein a throttle valve 13 fixed to a shaft 14 rotatably mounted in the base section 2. As illustrated in the drawing, the throttle 13 is in its closed position, and suflicient clearance is provided between the periphery of thethrottle and the mixture conduit 12 to permitair to flow around the throttle valve during idle operation of'the engine. Other modes'of providing air downstream from the closed throttle valve may be substituted for the partially open throttle valve'illustrated. For example, the throttle valve may be .completely closedand an air by-pass provided around the throttlevalve. "Such a by-pass is normally provided with an adjusting screw for controlling the amount of air flow- .ing therethrough during idle operation, as illustrated in UnitedStates'Patent 2,376,228. Fixed to one end'of the ,throttle, shaft ;14 .projecting outwardly. from the, base see- 3 tion 2 is a control lever 16 having an eye 17 for receiving a control link. An adjusting screw 18 is threadably mounted in a pair of inturned flanges 19 and 20 on the throttle control lever 16 and engages a stop 22 on the exterior of the base section 2 to permit adjustment for adequate clearance at idle setting between the throttle valve 13 and the mixture conduit 12. The fully open position of the throttle valve is limited by an iuturned flange 23 on the throttle lever, and a second stop 24 on the base section 2. The wide-open position of the throttle valve 13 may be adjusted by bending the flange 23 on the throttle control lever 16.

The cover section 8 of the carburetor includes the portion of the mixture conduit 12 providing the air horn 9. Mounted in the air horn 9 is a choke valve 26 secured to a shaft 27 rotatably mounted in the walls of the air horn 9. Fixed to the choke shaft 27 is a small lever 28 having an inturned flange 29. Rotatably mounted on the choke shaft 27 is a larger lever 31 provided with means to receive a connecting control link (not shown). The larger lever 31 has a pair of projecting lugs 32 and 33 between which is received the flange 29 on the smaller lever 28. A spiral spring 34 encasing the choke shaft 27 engages both lug 32 on the large lever 31 and the lug 29 on the small lever 28 to urge the choke valve 26 closed. As shown in Fig. l, the choke valve 26 is wide open, but, when the choke valve is fully closed, the spring 34 permits a slight opening of the valve for the flow of air through the mixture conduit, responsive to engine suction. If desired, the choke valve 26 may be provided with a conventional thermostatic control for urging the choke valve closed during warm-up, and a conventional suction motor control for opening the choke valve slightly when the eugine first fires during starting. The cover section 8 also contains a threaded fuel inlet 41 leading to the fuel chamber 6. A housing portion 42, having a top 43, in the cover section 8 contains various mechanisms to be referred to hereafter.

Mounted in the fuel chamber 6 in the body section 4 is a float valve 44 which controls a needle valve assembly (not shown). The float valve is responsive to rise and fall of the fuel level in the chamber to close and open the needle valve assembly. As illustrated in the drawing, an internal vent 46, in this instance including a balance tube 47, connects the fuel chamber 6 above the normal fuel level and the air horn 9. The purpose of the balance tube is to maintain substantially the same pressure on the fuel in the fuel chamber 6 and in the air horn 9, and compensate for a drop in the pressure of the air as it passes through the air cleaner. Opening into the fuel chamber 6 is a main orifice 51 which is connected by a passage 52 to a main fuel passage 53. A metering rod 54 is received in the main orifice 51 for varying the effective size of the orifice by a mechanism (not shown) in the housing 42. The mechanism is actuated by the position of the throttle valve 13 to admit more fuel when the throttle is open. The main fuel passage 53 terminates in a main nozzle 56 which discharges into the venturi cluster 7. The aforementioned fuel circuit provides fuel for the engine during normal and high-speed operation. During idle operation of the engine, fuel is drawn from the main fuel passage 53 through an idle tube 57, from which it passes through a passage system 8 to a chamber 59 in the base section 2 of the carburetor. A port 61 connects the chamber 59 and the mixture conduit 12 and has a portion opening downstream of the fully closed throttle valve 13. A passage 62 connects the chamber 59 with an idle adjustment port 63. An adjusting screw 64 provided with a needle valve 65 adjusts the eflective opening of the port 63. With the throttle valve 13 closed, fuel is drawn through the idle ports 61 and 63 by engine suction. During normal and high-speed operation, the throttle valve 13 is open and fuel is drawn through the main fuel nozzle 56 by the passage of air through the venturi cluster 7.

During the transition from idle to normal operation,

the throttle valve 13 is opened from the closed position illustrated in Fig. 1. Upon opening the throttle valve, the idle system gradually ceases to function, and the main fuel system gradually starts to function. An accelerating pump system is provided for adding a slight additional amount of fuel through a nozzle 68 and into the venturi cluster 7, responsive to initial opening movement of the throttle 13 from the closed position. The pump actuating mechanism is contained in the housing 42.

As shown in Fig. 1, an air passage system 71 through the carburetor body and base connects the air horn 9 and the mixture conduits (as 12) downstream from the throttle valves (as 13) in their closed position. The passage system 71 includes a single inlet passage 72 opening into the air horn centrally of the mixture conduits and into a crossover passage 73, between its ends which connect with branch passages 74 each opening through slots 75 into one of the mixture conduits 12. Only one branch passage 74 is shown. A valve assembly 76 for closing the passage system 71, and for metering the flow of air through the passage system 71, is mounted in the air horn 9, and is secured to the carburetor body 4, preferably by bolts 77.

Referring to Figs. 2 and 5, this embodiment of the valve assembly includes a substantially T-shaped body 78 having a leg 79 and a head 81. A pair of bolt holes are provided in the head for receiving bolts 77 threaded into the carburetor body 4 to secure the valve assembly to the body. Between the bolt holes is a third hole 82 providing a valve seat and an opening for the passage of air into the air passage 72. Fixed to the foot 83 of the leg 79 by a rivet 84 is one end of a temperature responsive, bimetallic actuating arm 86. Secured to the other end of the arm 86 is a frusto-conical valve 87 which engages the valve seat 82 to close the passage 72. When the assembly is completed, the arm 86 should be arched slightly against its inherent resiliency when the valve 87 is closed against the seat 82. To dampen the actuating arm 86, particularly against vibration and noise, a dampening member or bridge 88 is fixed by the rivet 84 between the actuating arm 86 and the valve body 78. The damp ening member 88 is maintained in alignment with the arm 86 by abutting engagement between the end of the dampening member 88 and an offset portion 91 on the body 78. Similarly, the actuating arm 86 may be maintained in alignment by extending the offset 91 on the valve body, but this should not be necessary, because the actuating arm 86 will stay in proper alignment through engagement of the valve 87 fixed to the other end of the arm 86 and the valve seat 82. The valve 87 is rigidly attached to the actuating arm 86 by a rivet 92. Between the head of the rivet 92 and the arm 86 is a washer 93. The dampening member 88 has its end nearest the frusto-conical valve 87 bent up slightly as at 94 to lightly engage the actuating arm 86, which is slightly arched, as previously described.

It is necessary that the bimetal actuating arm 86 and dampening member 88 be responsive, as nearly as practicable, to the temperature of the air in the air horn 9. The valve body 79 should be of low heat conductivity material, as steel and is insulated from the carburetor body 4 by an insulating gasket 97. In some practical applications, this has been found to provide suflicient insulation so that the actuating arm is not substantially affected by the heat in the carburetor body.

The arm 86 and dampening member or bridge 88 are more completely insulated from the heat of the carburetor body and the valve body, as illustrated in Fig. 3. In this embodiment, the shank 101 of the rivet 84 is completely insulated by an insulating sleeve 102 from the walls of the holes in the body 78, dampening member 88, and actuating arm 86. An insulating member 103 is inserted between the dampening member 88 and the valve body 78. An insulating member 104 is also inserted between the actuating arm 86 and a U-shaped clip 105, to be further described hereinafter. The lower head of the rivet is also insulated from the valve body 78, and similar insulation may be provided-between -the upper head of-the rivet and the U-shaped clip- 1 05. The 'insulatingmember between the valvebody and the lower :head of :therivetis not absolutely necessary, but retards the flow of heat -into the rivet. Gasket 97 would norm-ally also he: used -with this embodiment.

In the embodiment-illustrated in Figs. 4 and 15, the valve 107 is loosely secured to .the actuating arm to permit slight play between the actuating :arm 86 and the valve 107 to facilitate-proper and automatic alignment of the valve and-the valveseat 82. A stem 108-on the valve 107 projects through an enlarged hole 109 in the actuating arm 86, and a True-Arc type spring washer 11.1 grips the stem to permit play 'in all directions. The-stem 108 is substantially smaller-than the hole 109 in the actuating arm. In-this embodiment it is necessary to control within certain "limits the 'up-and-down movement of the valve 107 with respect to'the arm 86 in order to properly calibrate the carburetor. 'In the preferred embodiment about .005 inch has been found to be satisfactory.

In the embodiments of Figs. 3-5, alignment of the valve seat 82, dampening member 88, and actuating arm 86 is maintained by a U-shaped clip 105 which engages the-side edges of members 86 and '88 and the valve body 78. In Fig. 3 the sides of the U-shaped clip may be insulated from the thermostatic-members by suitable insujla-ting material.

It has been found desirable toform the frusto-conical cone faces-of the valves 87 and 107 with an interior angle a (Fig. 2) of about 50. When the valve is open, metering of air through the hole 82 is controlled in part bythe length of the'frusto-conical valve. Shortening the valve increases the how of air into the passage. The frustoconical valve 87 or 107 permits the valve to open slowly, without any substantial or noticeable increase in engine speed, and permits a controlled metering of air as the valve opens a greater amount in response to increases in air temperature. The valve is preferably made of brass.

Both the dampening member or bridge 88 and the actuating arm 86should be of the same bimetallic material in order to function properly. Otherwise, one would open more rapidly than the other, and calibrationof the carburetor would be made more difficult. In Figs. 3-5 the valve body is provided with a hole 114 near the foot 83 of the leg 79. This hole facilitates bending the leg 79 to adjust the valve 107 and valve seat '82, and further retards the flow of heat toward the connection between the valve body, dampening member, and actuating arm.

The operation is as follows: When the engine is started,

the choke valve 26 is maintained closed, either by manual positioning of lever 31, or by an automatic choke. As the engine warms up, the choke 26 is progressively opened until it is in its *fully open position, as shown in Fig. 1, when the engine is at normal operating temperatures. When the throttle 13 is opened, the idle system ceases to function, and fuel is drawn through the main nozzle 56 by the rush of air through the venturi cluster 7. To assure a smooth transition from idle to normal fuel operation, additional gasoline is injected into the venturi cluster 7 by the pump system through thepump nozzle 68. The valveassembly 76 is closed when the air in the air horn is at normal temperature. The valve is maintained closed both by the resiliency in the actuating arm 86 pressing the valve 87 or 107 against the valve seat 82, and by suction in the air passage 71 holding the valve on the valve seat. In the normal operating temperature range, it may be desirable on a particular engine to adjust the valve spring so that should the engine speed drop below the normal idle speed, the engine suction is lowered sufiiciently to permit the spring 86 to open the valve 87 or 107, admitting more air to the mixture conduit '12 through slot 75, leaning out the combustible mixture, thereby increasing the engine speed. As is 'Well'understood1in the art, proper manual adjustment of screws-64 set the mixture for idle and idle speed is adjusted by SCFeWf'18. The rvalve sassemhly iiS Icalibrated .totopen atla temperature slightly ;above -.the mormal air temperature. 'For .example, *if the mormalpper'ating .air temperature is ,1116 valve assembly .should zopenzbetween and The amount of opening .of the valve increases with an. increase in air. temperature, and, because of the zfrustoconical valve, theamount of :air entering'the-mixture conduit through the passage is metered. The frusto-conical valve also prevents asnap. or popopening-iof thewalve,as would result with otherttypes of valves such as :a fiatvalve engaging the valve seat. Sudden fulltopeningoftheyalve causes an almost immediate-and substantial rise:in.engine speed, which is'undesi-rable. As the engine becomeshotter, fuel will vaporize more rapidly in the fuel chamber and pass into the air horn. Thus, notonly'is the density of the air decreased, :but fit also contains excessive zfuel vapor, which results in an excessively rich idle mixture.

As mentioned previously, the throttle valve is not .tightly close'din the mixture conduit during idle operation, "but is open slightly to permit air around the throttle valve by-setting screw 18. Alternately, a by-pass around the throttle :valve, .or any other meth'od of admitting idle air to the mixture conduit downstream from the throttle valve, may be utilized. If such an auxiliary idle passage is utilized, .the supplementary .air passage may be combined therewith. Incoming air temperature is closely related to the engine temperature as follows: The engine is cooledby waterpassingzthrough,a'radiator, and the air entering the air cleaner normally is picked up .after it' has passed through the radiator core, cooling the water. Therefore, .as the engine-temperature increases, the'water temperature increases, as does the air temperature.

It is especially important that valve mount 79 and the thermostatic strip be located so as to accurately-sensethe temperature of the incoming air-without, at the same time, interfering with direct access of the air :to the respective mixture conduits and .fuel nozzles therein. For instance, these ports may be placed, as shown, directly in or above the dividing wall between adjoining barrels in a dual'or four-barrel carburetor. It should beunderstood that .a four barrel carburetor is merelytwodualscombined and there is a wall between the pair of primaries and a wall between the pair of secondaries.

Although this invention has been described'with particular reference tocertain features, materials, functions, and embodiments, various .changes :will :be apparent to one skilled in'the art, and .the invention is therefore not to be limited to such features, materials, functions, and embodiments,.except as set forth ,in-the following claims.

I claim:

1. In a carburetor, aplurality of mixture conduits hav- -ing a common .air inlet, -a main fuel nozzle discharging into each of said conduits, a throttle valve in at least one of said conduits, means to discharge idling fuel'into said latter conduit-posterior'to said throttle when closed, an air duct leading'from a port in saidair inletbetween said conduits to said latter conduit posterior to said throttle, and a thermostatic valve controlling said ;port, said valve being located substantially betwe'ensaid-conduits so as to sense the "temperature of the incoming :air and adjust said port accordingly without interfering with direct access of said air to saidconduits and fuel nozzles.

2. In a carburetor having mixture conduits with acornmon air inletand a pluralityof mixture outlets, throttles for controlling the flow through said mixture conduits, a fuel supply for said carburetor, an idlefuelpassage connected with said fuel supply and "having :an outlet in one of said mixture conduits posterior-of one of said throttles, and fuel metering-means in said passage calibrated to deliver a rate of fuel flow to said mixture conduit proportional to the rate of air flow through said mixture conduit for proper operation ofthe engine at idle speed within the ordinary range of ambient temperatures; a hot idle-compensator system forsaid.carburetor'independent of said fuel metering means in said fuel passage for modifying the proportions of fuel to air delivered by said carburetor, said hot idle compensator system comprising, an air passage in said carburetor, an inlet for said air passage connected with said air inlet for said mixture conduit anterior of said throttle valve, an outlet for said air passage connected with the outlet of one of said mixture conduits posterior to one of said throttles to form a supplemental air by-pass around one of said throttles, a metering valve controlling the flow of air through said air passage, and thermostat means responsive to ambient temperature for operating said valve to vary the flow through said passage as air flow temperatures exceed the ordinary range of ambient air temperatures, said hot idle compensator system acting to compensate for the effect of high ambient temperature tending to enrich the mix ture supplied through said fuel passage at engine idle speed.

3. In a carburetor having a plurality of mixture conduits located side by side with separate inlets and with separate outlets spaced by a dividing Wall, throttle valves controlling the flow through said mixture conduits, a fuel supply for said carburetor, idle fuel passage means connected with said fuel supply and having a pair of outlets in said mixture conduits posterior of said throttles, and fuel metering means in said passage means calibrated to deliver a rate of flow of fuel to each of said mixture conduits which is proportional to the rate of air flow to said mixture conduits for proper operation of the engine at idle speed within the ordinary range of ambient temperatures; a hot idle compensator system independent of said fuel metering means in said fuel passage means for modifying the proportions of fuel to air at the outlet of said mixture conduits, said hot idle compensator system comprising an air passage means in said carburetor having an inlet communicating with the inlet to said mixture conduits and extending through said wall between said mixture conduits to separate outlets connecting with said mixture conduits posterior of said throttle valves to supply supplemental air at the outlets of said mixture conduits, a metering valve controlling the flow of air through the inlet of said air passage means, and thermo stat means mounted at the inlet to said mixture conduits responsive to ambient air temperature tending to operate said valve to open said inlet of said air passage means as air flow temperature approaches and exceeds the ordinary range of ambient temperatures, said hot idle compensator system acting to compensate for the effect of high ambient temperature tending to enrich the mixture supplied through said fuel passage at engine idle speed.

4. In a carburetor having mixture conduits with inlets and outlets, throttles for controlling the flow through said mixture conduits, a fuel supply for said carburetor, fuel passages connected with said fuel supply and having outlets in said mixture conduits posterior of said throttles, and fuel metering means in said passages calibrated to deliver a rate of fuel flow to said mixture conduits proportional to the rate of air flow to said mixture conduits for proper operation of the engine at idle speed within the ordinary range of ambient air temperatures; a hot idle compensator system independent of said fuel metering means in said fuel passage for modifying the proportions of fuel to air at the outlet of said mixture conduits, said hot idle compensator system comprising, an air passage in said carburetor connected with a mixture conduit posterior of a throttle valve to supply supplemental air at said carburetor outlets, a metering valve controlling the flow of air through said air passage, and a resilient mounting for said valve including thermostat means responsive to ambient air temperatures tending to resiliently urge said valve in a direction to open said valve to increase the flow through said air passage when air flow temperatures approach and exceed the ordinary range of ambient temperatures against the force of suction in said air passage tending to close said valve, said hot idle compensator system acting to compensate for the effect of high ambient temperature tending to enrich the mixture supplied through said fuel passages at engine idle speed.

5. In a carburetor having a mixture conduit with an inlet and an outlet, a throttle valve controlling the fiow through said mixture conduit, a fuel supply for said carburetor, a fuel passage connected with said fuel supply and having an outlet in said mixture conduit posterior of said throttle, and fuel metering means in said passage calibrated to deliver a rate of fuel flow to said mixture conduit proportional to the rate of air flow to said mixture conduit for proper'operation of the engine at idle speed within the ordinary range of ambient temperatures; a hot idle compensator system independent of said fuel metering means in said fuel passage for modifying the proportions of fuel to air at the outlet of said mixture conduit, said hot idle compensator system comprising, air passage means in said carburetor connected with the outlet of said mixture conduit posterior of said throttle valve and having an inlet connected with the inlet of said mixture conduit to form a by-pass around said throttle for supplying supplemental air to the fuel mixture, a metering valve controlling the flow of air through said air passage arranged to be urged closed by the force of suction in said'air passage, and a resilient mounting for said metering valve including thermostat means responsive to ambient air temperatures to yieldingly urge said valve open with a'force which increases as air flow temperatures increase to the upper limit and beyond the ordinary range of ambient temperatures, said hot idle compensator system acting to compensate-for the efiect of high ambient temperature tending to enrich the mixture supplied through said fuel passage at engine idle speed.

6. In a carburetor having a mixture conduit with an inlet and an outlet, a throttle valve for controlling the flow through said mixture conduit, a fuel supply for said carburetor, an idle fuel mixture passage provided with an air bleed connected with said fuel supply and having an outlet in said mixture conduit posterior of said throttle, and fuel metering'means in said passage calibrated to deliver a rate of fuel flow to said mixture conduit propor tional to the rate of air flow through said idle fuel passage to said mixture conduit for proper operation of the engine at idle speed within the ordinary range of ambient temperatures; a hot idle compensator system independent of said fuel metering means in said fuel passage for modifying the proportions of fuel to air at the outlet of said mixture conduit, said hot idle compensator system comprising, an air passage in said carburetor connected to supply supplemental air at the outlet of said mixture conduit, a metering valve controlling the flow of air through said air pas sage, and a mounting for said valve including a resilient temperature responsive means operated by ambient air temperature for positioning said valve for controlling the flow of air through said air passage, said mounting means and said valve being so related to said passage as to be opened by the resilient action of said mounting means when suction in said passage decreases at ambient air temperatures approaching or exceeding the limit of the ordinary range of ambient temperatures, said hot idle compensator system acting to compensate for the elfect of high ambient temperature tending to enrich the mixture supplied through said fuel passage at engine idle speeds.

7. In a carburetor having a mixture conduit with an air inlet and a fuel mixture outlet, at throttle valve controlling the fiow through said mixture conduit, a fuel supply for said carburetor, a main fuel system, an idle fuel mixture passage connecting said fuel supply with said mixture conduit posterior of said throttle, and fuel metering means in said idle fuel passage calibrated to deliver a rate of fuel flow to said mixture conduit proportional to the rate of air flow through said fuel mixture passage for operation of the engine at idle speed; a hot idle compensator system independent of said fuel metering means in said fuel passage for modifying the proportion of idle fuel to air at the outlet of said mixture conduit, said hot idle compensator system comprising an air passage in said carburetor connected with the outlet of said mixture conduit posterior of said throttle valve to supply supplemental air at said outlet, a metering valve controlling the flow of air through said air passage, and thermostat means responsive to ambient air temperature for operating said valve to vary the flow through said air passage as air flow temperature increases.

8. In a carburetor having a pair of mixture conduits provided with a common air inlet, a fuel bowl, main and idle fuel systems connecting said fuel bowl and said mixture conduits, a throttle valve in each mixture conduit, air by-pass passageways leading from a common inlet port in said air inlet to their respective mixture conduits posterior to the throttle valves, and a temperature responsive valve assembly in said common air inlet to control the flow of air through said common inlet port.

9. In a carburetor having a pair of mixture conduits provided with a common air inlet, a fuel bowl, main and idle fuel systems connecting said fuel bowl and said mixture conduits, a throttle valve in each mixture conduit, air by-pass passageways leading from a common inlet port in said air inlet to their respective mixture conduits posterior to the throttle valves, and a temperature responsive valve assembly in said commo'n air inlet to control the flow of air through said common inlet port, said valve assembly comprising a body having a valve seat, a closure member to releasably engage said seat, a temperature responsive actuating arm secured to said body at one end and to said closure member at the other end thereof and responsive to changes in temperature to open and close said closure member relative to said seat, and a damping member of thermostatic material fixed to said body and lightly engaging said thermostatic arm intermediate its ends.

10. In a carburetor having a pair of mixture conduits provided with a common air inlet, a fuel bowl, main and idle fuel systems connecting said fuel bowl and said mixture conduits, a throttle valve in each mixture conduit, air by-pass passageways leading from a common inlet port in said air inlet to their respective mixture conduits posterior to the throttle valves, and a temperature responsive valve assembly in said common air inlet to control the flow of air through said common inlet port, said valve assembly comprising a body having a valve seat and a valve to releasably engage said seat, a temperature responsive actuating arm fixed to said seat at one end and secured to said valve at the other end thereof and responsive to changes in temperature to engage and disengage said valve and said seat, and a temperature responsive thermostatic damping member fixed to said body at the same location where said actuating arm is fixed to said body, and lightly engaging said actuating arm between the ends thereof.

11. In a carburetor having a pair of mixture conduits provided with a common air inlet, a fuel bowl, main and idle fuel systems connecting said fuel bowl and said mixture conduits, a throttle valve in each mixture conduit, air by-pass passageways leading from a common inlet port in said air inlet to their respective mixture conduits posterior to the throttle valves, and a temperature responsive valve assembly in said common air inlet to control the flow of air through said common inlet port, said valve assembly comprising a body having a valve seat and a valve to releasably engage said seat, a temperature responsive actuating arm fixed at one end with respect to said body and secured to said valve at the other end thereof and responsive to changes in temperature to engage and disengage said valve and said seat, and means comprising an opening through said body adjacent the fixed end of said arm to retard the flow of heat from said seat to said arm and to locally weaken said body to facilitate adjustment between said valve and said seat.

12. In a carburetor having a pair of mixture conduits provided with a common air inlet, a fuel bowl, main and idle fuel systems connecting said fuel bowl and said mix ture conduits, a throttle valve in each mixture conduit, air by-pass passageways leading from a common inlet port in said air inlet to their respective mixture conduits posterior to the throttle valves, and a temperature responsive valve assembly in said common air inlet to control the flow of air through said common inlet port, said valve assembly comprising a body having a valve seat and a valve to releasably engage said seat, a temperature responsive actuating arm fixed to said seat and loosely secured to said valve to permit said valve to move and properly engage said seat.

13. In a carburetor having a pair of mixture conduits provided with a common air inlet, a fuel bowl, main and idle fuel systems connecting said fuel bowl and said mixture conduits, a throttle valve in each mixture conduit, air by-pass passageways leading from a common inlet port in said air inlet to their respective mixture conduits posterior to the throttle valves, and a temperature responsive valve assembly in said common air inlet to control the flow of air through said common inlet port, said valve assembly comprising a body having a valve seat, a valve with a conical face adapted to engage said seat, an arm fixed at one end to said body and loosely secured to said valve at its other end to permit said valve to move and center said conical face to properly engage said seat, and a temperature responsive dampening bridge fixed to said body and lightly engaging said actuating aim intermediate its ends.

14. A carburetor comprising an air and fuel mixture conduit therethrough having an inlet and an outlet, a throttle valve within said mixture conduit for controlling the flow of air and fuel mixture through said mixture conduit, a fuel supply for said carburetor, an idle fuel system connected to said fuel supply and having an outlet port in said mixture conduit posterior of said throttle to deliver a fuel and air mixture to said mixture conduit outlet for proper operation of the engine at idle speed within the ordinary range of ambient temperatures, a hot idle compensator system independent of said idle fuel system for modifying the proportion of idle fuel to air mixture at said mixture conduit outlet, said hot idle compensator system including an air passage in said carburetor connected from said mixture conduit outlet posterior of said throttle valve to said mixture conduit inlet to supply supplemental air at said mixture conduit outlet, a metering valve controlling the flow of air through said air passage, and thermostat means in said mixture conduit inlet and responsive to ambient air temperature passing into said mixture conduit for opening said valve to provide a flow of air through said air passage as said ambient air temperature increases beyond a predetermined temperature.

References Cited in the file of this patent UNITED STATES PATENTS 1,886,368 Blancke Nov. 8, 1932 2,257,972 McCollum Oct. 7, 1941 2,675,792 Brown et a1. Apr. 20, 1954 2,793,633 Heftler et a1. May 28, 1957 

